In recent years, various types of processing have been proposed with regard to transfer errors which occur when moving image data is transferred using the Internet, etc.
In MPEG4 (Moving Picture Experts Group 4), portions where a transfer error has occurred are discarded by using a resynchronization marker, RVLC (Reversible Variable Length Code), etc., so that the error tolerance is improved.
Furthermore, as error concealment technology for hiding errors which have occurred so as to be made inconspicuous, a process has been proposed in which, by using the correlation characteristics in the time direction of a moving image, a previous frame is played back, or the image is replaced with information from the same position as that of a past frame.
However, when error tolerance is improved through the use of RVLC, it has been pointed out that the coding efficiency is decreased. Furthermore, there are problems in that processing for the above-mentioned error concealment is complex, and coping with a sudden change in an image, such as a scene change, is difficult.
Accordingly, error concealment technology has been proposed in which, when hierarchically coded image data is transferred, in a case where some of a transmitted frame is lost and the complete frame is not transmitted to the reception side, the lost frequency components are generated on the basis of the data which has been received and stored on the reception side up to the time the loss has occurred, and frequency components of a higher-order hierarchy are reconstructed (refer to, for example, Japanese Unexamined Patent Application Publication No. 10-243400 (page 7)).
However, when low-level information, of which there is a large amount in image information, is lost, there is the problem of image quality deterioration.